How Mass Appraisal Works

Sales ratio studies, “are the primary administrative tool for establishing or reviewing municipal assessments.”[1] The sales ratio study measures assessment quality by comparing assessed values against recent real estate sales. The more recent the sales the more reliable the study. We typically use sales from the past two years.

Between April 1, 2023 and March 31, 2025 (the most recent past twenty-four months for which we had data at the time the study was performed for this adjustment), town wide, we had 136 qualified sales. The median ratio for those sales was 87%.

https://www.krtappraisal.com/dist/rockport-me Follow this link to review sales.

Typically, the lowest acceptable ratio is 91% (more on this in the Ratio section). To discern what adjustments are needed to bring the new ratio up, we divide the sales into their proper grouping, as mentioned earlier.

Since single-family dwellings are the largest grouping within the town, I’ll isolate them for this illustration. Of Rockport’s 136 qualified sales, 86 were single-family dwellings.

We first calculate each sale’s A/S ratio, that’s the Assessed value divided by the Sale price.  An assessed value of $350,000 divided by a sale price of $350,000 has an A/S ratio of 1.0 or 100%. If that same property sold for $400,000, its A/S ratio would be .875, or 88%.

Once all 86 ratios have been determined, they are sorted in ascending order. We next locate the median. The median is the middle ratio. That middle ratio was .87. The median ratio for single-family dwellings is 87%.

[1] Course PT103 – Valuation of Real Estate, Published by Maine Revenue Services